/*
 * ------------------------------------------------------------------------
 *
 *  Copyright by KNIME AG, Zurich, Switzerland
 *  Website: http://www.knime.com; Email: contact@knime.com
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License, Version 3, as
 *  published by the Free Software Foundation.
 *
 *  This program is distributed in the hope that it will be useful, but
 *  WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, see <http://www.gnu.org/licenses>.
 *
 *  Additional permission under GNU GPL version 3 section 7:
 *
 *  KNIME interoperates with ECLIPSE solely via ECLIPSE's plug-in APIs.
 *  Hence, KNIME and ECLIPSE are both independent programs and are not
 *  derived from each other. Should, however, the interpretation of the
 *  GNU GPL Version 3 ("License") under any applicable laws result in
 *  KNIME and ECLIPSE being a combined program, KNIME AG herewith grants
 *  you the additional permission to use and propagate KNIME together with
 *  ECLIPSE with only the license terms in place for ECLIPSE applying to
 *  ECLIPSE and the GNU GPL Version 3 applying for KNIME, provided the
 *  license terms of ECLIPSE themselves allow for the respective use and
 *  propagation of ECLIPSE together with KNIME.
 *
 *  Additional permission relating to nodes for KNIME that extend the Node
 *  Extension (and in particular that are based on subclasses of NodeModel,
 *  NodeDialog, and NodeView) and that only interoperate with KNIME through
 *  standard APIs ("Nodes"):
 *  Nodes are deemed to be separate and independent programs and to not be
 *  covered works.  Notwithstanding anything to the contrary in the
 *  License, the License does not apply to Nodes, you are not required to
 *  license Nodes under the License, and you are granted a license to
 *  prepare and propagate Nodes, in each case even if such Nodes are
 *  propagated with or for interoperation with KNIME.  The owner of a Node
 *  may freely choose the license terms applicable to such Node, including
 *  when such Node is propagated with or for interoperation with KNIME.
 * ---------------------------------------------------------------------
 *
 * History
 *   Sep 25, 2019 (julian): created
 */
package org.knime.base.node.io.filehandling;

import java.nio.file.Path;
import java.util.List;

import org.knime.core.data.DataTableSpec;
import org.knime.core.node.CanceledExecutionException;
import org.knime.core.node.ExecutionContext;
import org.knime.core.node.ExecutionMonitor;
import org.knime.core.node.InvalidSettingsException;
import org.knime.core.node.streamable.RowOutput;

/**
 * Interface providing methods to process paths and pushes rows to a given {@link RowOutput}.
 *
 * @author Julian Bunzel, KNIME GmbH, Berlin, Germany
 * @since 4.1
 */
public interface FilesToDataTableReader {

    /**
     * Creates and returns a {@link DataTableSpec} based on the specifications of the incoming data.
     *
     * @param paths {@link Path Paths} leading to the data
     * @param exec ExecutionMonitor to provide progress and cancellation
     * @return DataTableSpec
     * @throws InvalidSettingsException Thrown if spec could not be created
     * @throws CanceledExecutionException if progress was canceled
     */
    DataTableSpec createDataTableSpec(List<Path> paths, ExecutionMonitor exec) throws InvalidSettingsException,
    CanceledExecutionException;

    /**
     * Creates and returns a {@link DataTableSpec} based on the specifications of the incoming data.
     *
     * @param paths {@link Path Paths} leading to the data
     * @return DataTableSpec
     * @throws InvalidSettingsException Thrown if spec could not be created
     */
    default DataTableSpec createDataTableSpec(final List<Path> paths) throws InvalidSettingsException {
        try {
            return createDataTableSpec(paths, new ExecutionMonitor());
        } catch (CanceledExecutionException e) {
            //this can not happen since no one can cancel the execution monitor
            throw new IllegalStateException(e);
        }
    }

    /**
     * Pushes data rows to a {@link RowOutput}.
     *
     * @param path Path leading to a file
     * @param output The RowOutput of the node
     * @param exec ExecutionContext
     * @throws Exception Thrown if row could not be pushed
     */
    void pushRowsToOutput(Path path, RowOutput output, ExecutionContext exec) throws Exception;

}
